INTEGRATING OF GEORADAR ANS SEISMIC STUDIES OF THE TAILINGS DAM

Identification of water-saturated zones in the tailings dams is an actual scientific and practical task in terms of providing, first of all, their mechanical strength and filtration stability. The prevention of accidents in tailings is complicated by the circumstance that the processes of increased filtration, appearing and developing in the dam body, are not fixed on the initial stages by visual and traditional methods. Insufficiency, from the point of view of data completeness, of networks of piezometric boreholes on tailings dams does not allow solving the tasks of necessary information hydrological support. At the same time, the use of active- sounding geophysical study methods allows obtaining sufficiently detailed information about the peculiarities of the internal structure of the tailings dam and the degree of water saturation of the composing soils. A reasoned choice of geophysical methods, as well as their combination, allows increasing the level and reliability of obtained data at subsurface studies. The paper presents the results of in-situ experiments on the study of the tailings dam of the mining enterprise by different in nature wave GPR (georadar) and seismic methods. A comparative analysis of the conducted studies has allowed clarifying the internal structure and assessing the dam’s condition, paying special attention to the identification of local zones of increased water saturation and filtration. Based on the calculated correlation coefficient of electromagnetic and seismic wave velocity values, it was revealed that synchronization of geophysical surveys allows significantly increasing the reliability of in-situ determinations, as well as obtaining more reliable data. The results of the studies are the basis for predicting the most vulnerable places (zones) of a bulk ground hydraulic facility, as well as the localization of water-saturated areas in the body of the ground structures with greater reliability and performance.

The operation capacity of the construction of a rockfill dam with a concrete screen accommodated to the conditions of Pskemskaya HPP

Introduction. A rockfill dam with a concrete screen is considered as an alternative to a traditional earth-faced rockfill dam in the process of designing a high-pressure Pskemsky hydraulic facility in Uzbekistan. A rockfill dam with a concrete screen has several strengths. However the geological structure of the dam site complexifies the application of a rockfill dam with a concrete screen, because dam boards have a deep layer of gritstone. There arose a need to study the stress-strain state of a 190 m dam in 2D and 3D settings. Materials and methods. The finite element method (FEM) and numerical modeling were employed to study the stress-strain state of the dam. The modulus of linear deformation of the rockfill top reaches 480 MPa, the one of the rockfill bottom — 240 MPa. The concrete deformation module was taken as equal to 29 and 12 hPa. The analysis took account of the isolation joint that separated the central part of the screen from its bank parts, while the contact surface of the screen and the dam body had a layer of friction-reduction emulsion. Results. The research performed by the co-authors enabled them not only to analyze the screen’s displacements and strains, but also to consider longitudinal forces and bending moments. Conclusions. A rockfill dam with a reinforced concrete screen has proven a reliable structure capable of accommodating static forces. However rock needs to be thoroughly compacted, and the water basin must be filled gradually. In this case, concrete compressive/tensile strength values will be sufficient in the 3D environment. The heterogeneity of the geological composition of the dam base cannot disintegrate the screen, because vertical joints compensate for the tensile stress arising inside.

METHODS TO CALCULATE THE SOCIAL-ECONOMIC DAMAGE CAUSED BY FLOODS

The volumes of the water reservoirs flooded with high-rise hydrotechnical facilities, including high-rise earth dams, often range from several hundreds of millions to tens of billions of cubic meters and even more. The present paper describes the methodology to calculate the social-economic losses for the facilities flooded and destroyed by a tsunami-type wave in case of a possible high-rise hydraulic facility accident.The social-economic damage caused by a dam failure can be viewed as a sum of dam-age caused by human victim, destruction of hydraulic and industrial facilities and agricul-ture, pond economy, forestry and communal services.

EPANET Modelling of a High Head Pumped-Storage Hydropower Facility

A complex hydraulic facility is modelled in EPANET. The system consists in an underground high head Hydro Power Plant (HPP) and a Pumping Station (PS), operating in a pumped-storage hydropower scheme with three reservoirs. The complexity of the system is due to its unusual configuration, where the PS discharges the water directly into the HPP penstock. The PS is equipped with 2 × 10 MW pumps. The HPP is equipped with 2 × 75 MW Francis turbines. The simulations allow assessing the energy production and/or consumption in various scenarios, offering a tool to decision makers, to wittingly choose the operation mode of the facility.